Biological changes in C57BL/6 mice following 3 weeks of inhalation exposure to cigarette smoke or e-vapor aerosols

Inhal Toxicol. 2018 Nov-Dec;30(13-14):553-567. doi: 10.1080/08958378.2019.1576807. Epub 2019 Mar 8.


We compared early biological changes in mice after inhalation exposures to cigarette smoke or e-vapor aerosols (MarkTen® cartridge with Carrier, Test-1, or Test-2 formulations; 4% nicotine). Female C57BL/6 mice were exposed to 3R4F cigarette smoke or e-vapor aerosols by nose-only inhalation for up to 4 hours/day, 5 days/week, for 3 weeks. The 3R4F and e-vapor exposures were set to match the target nose port aerosol nicotine concentration (∼41 µg/L). Only the 3R4F group showed postexposure clinical signs such as tremors and lethargy. At necropsy, the 3R4F group had significant increases in lung weight and changes in bronchoalveolar lavage parameters, as well as microscopic findings in the respiratory tract. The e-vapor groups had minimal microscopic changes, including squamous metaplasia in laryngeal epiglottis, and histiocytic infiltrates in the lung (Test-2 group only). The 3R4F group had a higher incidence and severity of microscopic findings compared to any e-vapor group. Transcriptomic analysis also showed that the 3R4F group had the highest number of differentially expressed genes compared to Sham Control. Among e-vapor groups, Test-2 group had more differentially expressed genes but the magnitude of gene expression-based network perturbations in all e-vapor groups was ∼94% less than the 3R4F group. On proteome analysis in the lung, differentially regulated proteins were detected in the 3R4F group only. In conclusion, 3-weeks of 3R4F exposure induced molecular and microscopic changes associated with smoking-related diseases in the respiratory tract, while e-vapor exposures showed substantially reduced biological activities.

Keywords: 3R4F; MarkTen®; aerosols; e-cigarette; e-vapor; inhalation; mice; proteomics; transcriptomics.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Aerosols
  • Animals
  • Bronchoalveolar Lavage Fluid / chemistry
  • Bronchoalveolar Lavage Fluid / cytology
  • Carboxyhemoglobin / analysis
  • Electronic Nicotine Delivery Systems*
  • Female
  • Gene Expression Profiling
  • Mice, Inbred C57BL
  • Respiratory Function Tests
  • Respiratory Physiological Phenomena / drug effects
  • Respiratory System / drug effects*
  • Respiratory System / metabolism
  • Respiratory System / pathology
  • Smoke / adverse effects*
  • Tobacco Products / adverse effects*


  • Aerosols
  • Smoke
  • Carboxyhemoglobin